This paper deals with voltage maintenance of PV/FC/Storage DC microgrids under variable load demands. To reach this goal, a master-slave robust control strategy is suggested. Thus, the battery unit acts as the master system with a cascaded voltage controller. On the other hand, PV and FC sources serve as the slaves with their own sliding mode controllers. The PV and FC sources with boost converters supply the base power of the load while the storage unit with a buck-boost converter is responsible of the load changes in order to stabilize the whole system. The designed control strategy effectiveness is verified using MATLAB simulations on a DC microgrid in the presence of various load demands. The suggested control approach assures the regulation of the DC-bus voltage very well.